I want to add what I mean by distortion.
Normally, for non-architect landscape, distortion is not a problem, sometime it is even desirable. The distortion may add some advantagsours strentch.
For architect and architectural landscape, personally I can't torlerate distortion. This is one area Contax 35mm/3.5 needs a lot PS.
For protrature, this is really a war zone. For fashion portraits, believe me, professional photgraphers love that distortion to death. No distiotion means no sell. (Lips have to be blue, the model's expression must be good for Holloween movie's poster, and the movement of the legs and the arms must look like doing the DUI tests. etc.)
But for family album is different, this is what I use for my distortion criteria. If I shoot a famiy album with Contax 35mm/3.5, I'd have to make sure no one standing or sitting out of the middle 1/3rd zone. Otherwise for certain there is no sell. I hve much less concersn on this with 45mm or 80mm.